This invention relates to a spinning pack for wet spinning a large number of bicomponent filaments, particularly, bicomponent acrylic filaments and, more particularly, bicomponent acrylic filaments having the specific ability to develop a helical crimp on hot or hot/wet treatment because of a difference in shrinkage between the two components. (Bicomponent filaments having this ability are commonly referred to as "conjugate filaments".) The term "bicomponent filaments", as used herein, means filaments consisting of two components arranged either in a side-by-side or sheath/core configuration along the length of the filaments. The term "wet spinning" as used herein means a process in which a solution of fiber-forming polymer is extruded from a spinning pack through orifices directly into a liquid coagulation medium where the polymer is coagulated to form filaments that are further processed. Preferably, the spinning pack is immersed in the liquid coagulation medium. However, if desired, the spinneret may be placed a short distance (e.g. 0.5 to 2 cm) above the surface of the liquid medium.
Spinning packs useful for wet spinning bicomponent filaments are described in the prior art, for example, U.S. Pat. No. 3,176,345 describes a spinning pack consisting of stacked plates that are bolted together. Some of the plates have slots defining orifices and the remaining plates have hollow regions defining manifolds. The plates are arranged so that a slotted plate is sandwiched between two manifold plates. In operation of the pack two solutions under pressure are fed to the pack, one polymer spinning solution flows to the manifold plates on one side of the slotted plates and the other polymer solution flows to the manifold plates on the other side of the slotted plates. The two solutions combine in each of the slots of the slotted plates and are extruded from each slot as a single stream which, when coagulated, provides a bicomponent filament. One problem encountered in using this pack is that the distribution of the two components in the filaments is not uniform because the lower viscosity solution tends to wrap around the higher viscosity solution.